Web tracking mechanism



April 25, 1957 w. s. OWEN, JR, ETAL. 3,315,859

WEB TRACKING MECHANI SM Filed March 51, 1965 WILLIAM S- OWEN, JR- ROBERT F- SM! INVENTORS K BY 440 ATTORNEYS United States Patent Filed Mar. 31, 1965, Ser. No. 444,252 14 Claims. (Cl. 226--21) This invention relates generally to tracking systems, and more specifically to a web tracking mechanism to provide proper tracking in either direction of travel of a continuous web.

Web tracking mechanisms for assuring proper tracking of a continuous web threaded over a plurality of rollers are well known in the art. However, most of the prior known mechanisms that applicants are aware of are of relatively complicated construction and expensive to manufacture. Furthermore, these prior art mechanisms are limited in that they provide proper tracking in only one direction of web transport. Applicants improved web tracking mechanisms are believed to obviate all of the aforementioned disadvantages of prior known mechanisms.

It is well known that a web, threaded around a series of rollers, may have its travel position changed by tilting the axis of one of the rollers. In the case of a continuous web threaded over rollers and running in one direction only, tilting of one end of the roller upwards (the other end being relatively fixed) beyond a certain center" point, will produce web drift or movement along the rollers in one axial direction. See US. Patent No. 3,149,497, Haugen, Sept. 22, 1964.) Tilting the roller down below this center (or balance) point will produce movement in the opposite direction. If the direction of the web is reversed, the direction of web drift movement resulting from a tilting of the roller is reversed. The normal center (or balance) point will vary slightly in any system because of variations in roller centers, webs, pressures, etc., and will further change slightly during operation of any particular system because of eccentricity of parts, varying demands on the system, etc.

In summary, this invention broadly includes within its scope a web tracking system of the type having a correcting roller which is tiltable in response to a web travel correcting mechanism to correct any mistracking of the web. The correcting mechanism is movable in response to web travel in one direction to a first position in which it corrects any mistracking of the web. When the direction of web travel is reversed, the tilting mechanism is movable in response to the web travel to a second position in which it corrects any mistracking of the web. It is also possible in a modification of the invention to manually move the correcting mechanism between its first and second positions.

One of the objects of the present invention is to provide an improved web tracking system that will provide proper tracking for a continuous Web in either direction of transport of the web.

Another object of the invention is to provide an improved web tracking system of simple design and construction, thoroughly reliable and efiicient in operation, and economical to manufacture.

Another object of the invention is to provide an improved web tracking system ofthe type in which a correcting roller is responsive to a web .travel correcting mechanism for tilting the roller in a direction to correct any mistracking of the web, and in which the correcting mechanism is automatically conditioned to provide the proper correction in response to the direction of travel of the web.

Objects and advantages other than those set forth above will be apparent from the following description when read 3,3 15,859 Patented Apr. 25, 1967 in connection with the accompanying drawings, in which:

FIG. 1 is an exploded View in perspective of a web tracking mechanism constructed in accordance with one embodiment of this invention;

FIG. 2 is a fragmentary side elevation view in section of the pivotally mounted roller of the mechanism shown in FIG. 1;

FIG. 3' is a side elevation view of the cam disk of FIG. 1 for tilting the roller;

FIG. 4 is a fragmentary front elevation view, partly in section, of the mechanism in assembled form for tilting the roller of FIG. 1;

FIG. 5 is a fragmentary end elevation view of a modification of the invention;

FIG. 6 is a fragmentary front elevation view of the mechanism of FIG. 5 with a portion of the tilting disk broken off; and

FIG. 7 is a fragmentary front elevation view showing a modification of the mechanism of FIG. 6.

Referring to the drawings, a preferred embodiment of a web tracking mechanism according to the present invention is disclosed in FIGS. 1-4 as comprising a fixed shaft 8 having the inner race 10 of a spherical bearing secured thereto. The race 10 (see FIG. 2) pivotally supports a roller 12 by means of a pair of annular outer races 14 interposed between inner race 10 and the inner periphery of roller 12. The races 14 are secured together by screws 16 and arcuate spring washers 18, the ends of which are urged into frictional engagement with the inner periphery of roller 12 for securing the outer races 14 thereto. The shaft 8 has one end thereof positioned in a V-notch 20 in a side frame 22, and the opposite end thereof supported by a similar side frame 24. A web 26 is trained over roller 12, and is held into engagement therewith by any suitable web tensioning means, not

shown.

A web sensing means for sensing the edges of web 26,

and further being responsive thereto to actuate a web travel correcting mechanism for roller 12 is provided. The web sensing means comprises end caps 28'loosely mounted at the ends of roller ill (see FIG. 4), and secured together by rods 30 passing through complementary openings in races 14 and washers 18 to permit axially slidable movement of end caps 28 relative to roller '12.

End caps 28 are rotatable with roller 12 by virtue of the connection between rods 30, races 14 and washers 18. The end caps 28 have enlarged central openings 29 to permit pivotal movement of roller 12 relative to shaft 8. Although a pair of end caps 28 are used in this embodiment to sense lateral drift of web 26 in either direction, it

is possible to use only one end cap which is biased into en-. gagernent with an edge of web 26 by a spring or the like.

The aforementioned web travel correcting mechanism is responsive to both the roller 12 and one. of the end caps 28. The correcting mechanism comprises a cam' disk 32 loosely mounted on one of the end caps 28. The

disk 32 abuts an annular shoulder 31 on cap 28 (see FIG. 4 4) and is frictionally clutched to the end cap by means of a helical spring 34 encircling a grooved ring 35 press fitted onto end cap 28. The opposite ends of spring 34 are secure-d to a pin 36 on disk 32. Accordingly, disk 32 is responsive toboth the rotation and axial movement of end. cap 23. The disk 32 further has a pair of oppositely di-.

reoted circumferentially extending fingers 38, 38, one of which is efiective in one direction of rotationzof end cap 28 and hence one direction of travel of web'26, and the other finger is effective in the reverse direction of travel of web 26. The under surfaces of fingers 38, 38" form respective cam surfaces 40, 4t) terminating in shoulders 42, 42. Depending upon the direction of rotation of roller 12, the cam surfaces 40, slidably engage corresponding pins 44, 44 extending from brackets 46 mounted on frame 4. With the web travel in the direction noted in FIG. cam surface 40 engages pin 44 and slidably moves therelong until pin 44 engages shoulder 42. The pins 44, 44' re inclined at an angle with respect to the axis of shaft I (see FIG. 4), and are adjustable by means of eccentrics 8 extending through openings 50 in brackets 46, and seured to frame 24 by any suitable means such as screws 52.

In the operation of the embodiment of the invention lisclosed in FIGS. 14, let us assume that web 26 is being ransported in a direction rotating roller 12 in a counterlockwise direction as seen in FIG. 1. Accordingly, disk 2, by'virtue of spring 34, is turned in a counterclockwise lirection until shoulder 42 engages pin 44 whereupon furher movement of disk 32 is prevented as best seen in IG. 3. If web 26 should now drift or mistrack to the ight, end cap 28 and disk 32 will also be moved as a unit the right causing shoulder 42 to slide along pin 44. lince pin 44 is tilted downwardly, such sliding movement :auses the right end of roller 12 to tilt upwardly. This ivotal movement of roller 12 will cause web 26 to return 0 its original position. Now if the direction of web 26 .hould be reversed, roller 12 will now be rota-ting in a :lockwi-se direction causing shoulder 42 to engage pin l4. In this situation, if web 26 should mistrack to the 'ight, end cap 28 and disk 32 will be moved to the right :ausing shoulder 42 to slide downwardly along the upvardly tilted pin 44' resulting in a downward tilting movement of the right end of roller 12. This tilting movement 3f roller 12 causes web 26 to return to its original posiion.

In FIGS. and 6, the feature of automatically condizioning the tilting mechanism in response to the direction at web travel so that the roller may be tilted in the proper direction to correct any mistracking is eliminated. In- ;tead, the tilting mechanismmust be manually conditioned. lhe tilting mechanism is modified by eliminating cam disk 52 and spring 34, and utilizing an enlarged end cap 54. A pair of brackets 56, only one of which is shown, are provided, each cooperating with one of the end caps 54. Each bracket 56 further has pins 44, 44 extending therefrom, and the brackets 56 are manually movable together by virtue of an interconnecting bar 57 between two positions about an axle 58. A handle 60 is provided on one or both of the brackets 56 for selectively moving one or the other of the pair of pins 44, 44 into sliding engagement with end caps 54 depending upon the direction of travel of the web 26. Stop means 62 are provided for limiting the movement of handle 60 and brackets 56 between their two positions. Any suitable detent system, not shown, may be provided for releasably holding the brackets 56 in their respective positions.

If desired, only one of the brackets 56 may be used in the tracking system. However, in such case some suitable spring means must be incorporated in the mechanism to urge the end cap 54 into engagement with the corresponding pin in each direction of travel of the web.

In FIG. 7, the mechanism of FIG. 6 is altered by providing end cap 54 with a peripheral groove 64 for receiving the periphery of a roller 66 slidably mounted on pin 44'. This arrangement reduces the frictional forces developed between end cap 54 and the pin 44.

The invention has been described in detail with particular reference to preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention as described hereinabove, and as defined in the appended claims.

We claim:

1. In a web tracking mechanism, the combination comprising:

a support;

'a roller pivotally mounted on said support for supporting a web trained thereover for travel along a predetermined path;

Web s g means mounted at one end of said roller for rotation therewith and for axial movement relative to said roller in response to lateral drift of said web from said predetermined path; and

web travel correcting means including a first member inclined in one direction at an angle to the axis of said roller for engaging said web sensing means at one point, and a second member inclined in a different direction relative to the axis of said roller for engaging said web sensing means at a point substantially diametrically opposed from said one point, said correcting means further including means interrelating said web sensing means and said first and second members so that in a first position of said interrelating means corresponding to one direction of travel of said web only one of said first and second members is operative for maintaining the web travel along said predetermined path, and in a second position of said interrelating means corresponding to web travel in the opposite direction, said other of said first and second members is operative for maintaining said web along said predetermined path.

2. The invention according to claim 1 wherein said first and second members are pins, and said interrelating means comprises a movable bracket supporting said pins, and movable between said first position in which one of said pins operatively engages said web sensing means, and said second position in which the other of said pins operatively engages said web sensing means.

3. The invention according to claim 2 wherein said web sensing means comprises an end cap, and in said first position only said one pin engages the periphery of said end cap, and in said second position only said other pin engages the periphery of said end cap;

4. The invention according to claim 1 wherein said interrelating means is movable from one of said first and second positions to the other in response to a reversal in the direction of web travel along said path.

5. The invention according to claim 1 wherein said first and second members are pins, and said interrelating means comprises a disk rotatably mounted on said web sensing means, said disk in said first position having a first cam surface for riding on one of said pins until a first shoulder on said disk engages said one pin, and in said second position having a second cam surface for riding on the other of said pins until a second shoulder on said disk engages said other pin.

6. In a web tracking mechanism, the combination comprising:

a support;

a roller pivotally mounted on said support for supporting a web trained thereover for travel along a predetermined path;

web sensing means mounted at one end of said roller for rotation therewith, and for axial movement relative to said roller in response to lateral drift of said web from said predetermined path;

cam means rotatably mounted on said web sensing means;

a member inclined at an angle with respect to the axis of said roller; and

clutch means interposed between said cam means and said web sensing means whereby said cam means is moved into engagement with said member in response to travel of said web, said member and said cam means slidably cooperating to pivotally move said roller in a direction for returning said web to its predetermined path in response to movement of said web sensing means.

7. The invention according to claim 6 wherein said web sensing means comprises an end cap engageable by an edge of said web.

8. The invention according to claim 6 wherein said cam means comprises a disk.

9. The invention according to claim 8 wherein said disk has a cam surface terminating in a shoulder.

10. The invention according to claim 9 wherein said member comprises a pin along which said cam surface rides until said shoulder engages said pin.

11. The invention according to claim 8 wherein said clutch means comprises a spring.

12. The invention according to claim 11 wherein said spring encircles said end cap in frictional engagement therewith and has its opposite ends secured to said disk.

13. The invention according to claim 6 wherein a pair of substantially diametrically opposed members are inclined at an angle with respect to the axis of said roller, and said cam means is movable into engagement with one of said members in response to web travel in one direction, and into engagement with the other of said members in response to web travel in the opposite di- 1 rection.

14. The invention according to claim 6 wherein web sensing means are mounted at each end of said roller and are interconnected.

FOREIGN PATENTS 803,974 11/1958 Great Britain.

References Cited by the Applicant UNITED STATES PATENTS 2,927,210 3/1960 OMara. 2,98 9,256 6/ 1962 Selsted. 3,078,021 2/ 1963 Crownfield et a1.

M. HENSON WOOD, IR., Primary Examiner. R. A. SCI-IACHER, Assistant Examiner. 

6. IN A WEB TRACKING MECHANISM, THE COMBINATION COMPRISING: A SUPPORT; A ROLLER PIVOTALLY MOUNTED ON SAID SUPPORT FOR SUPPORTING A WEB TRAINED THEREOVER FOR TRAVEL ALONG A PREDETERMINED PATH; WEB SENSING MEANS MOUNTED AT ONE END OF SAID ROLLER FOR ROTATION THEREWITH, AND FOR AXIAL MOVEMENT RELATIVE TO SAID ROLLER IN RESPONSE TO LATERAL DRIFT OF SAID WEB FROM SAID PREDETERMINED PATH; CAM MEANS ROTATABLY MOUNTED ON SAID WEB SENSING MEANS; A MEMBER INCLINED AT AN ANGLE WITH RESPECT TO THE AXIS OF SAID ROLLER; AND CLUTCH MEANS INTERPOSED BETWEEN SAID CAM MEANS AND SAID WEB SENSING MEANS WHEREBY SAID CAM MEANS IS MOVED INTO ENGAGEMENT WITH SAID MEMBER IN RESPONSE TO TRAVEL OF SAID WEB, SAID MEMBER AND SAID CAM MEANS SLIDABLY COOPERATING TO PIVOTALLY MOVE SAID ROLLER IN A DIRECTION FOR RETURNING SAID WEB TO ITS PREDETERMINED PATH IN RESPONSE TO MOVEMENT OF SAID WEB SENSING MEANS. 